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SB10FD exits whole process on parameter error #126

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#128
Closed
SB10FD exits whole process on parameter error#126
#128

Description

@bnavigator
bnavigator
opened on May 17, 2020

In reference to #98 (comment):

[ben@voyagerS9:~]% python                                                                                                   [0]
Python 3.8.2 (default, Apr  8 2020, 14:31:25) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from slycot import synthesis
>>> from numpy import array
>>> A = array([[-1, 0, 0], [0, -12, -5], [0, 4, 0]])
>>> B = array([[2, 0], [0, 0.5], [0, 0]])
>>> C = array([[-0.5, 0, -0.5], [0, 0, 0], [-0.5, 0, -0.5]])
>>> D = array([[0, 0],  [0, 1], [0, 0]], dtype=float)
>>> synthesis.sb10fd(3, 2, 3, 1, 1, 100, A, B, C, D, 1e-7, None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/ben/src/Slycot/_skbuild/linux-x86_64-3.8/cmake-install/slycot/synthesis.py", line 2717, in sb10fd
    raise_if_slycot_error(out[-1], arg_list, sb10fd.__doc__)
  File "/home/ben/src/Slycot/_skbuild/linux-x86_64-3.8/cmake-install/slycot/exceptions.py", line 236, in raise_if_slycot_error
    raise globals()[exception](fmessage, info)
slycot.exceptions.SlycotArithmeticError: 
The Y-Riccati equation was not solved
successfully (the controller is not admissible or
there are numerical difficulties)
>>> synthesis.sb10fd(1,1,1,0,1,1,[1],[1],[1],[1],1e-3,1)
 ** On entry to SB10FD parameter number 20 had an illegal value
[ben@voyagerS9:~]%                                                                                                          [0]

The last drop out of the whole Python process should not happen. A simple Exception should be enough. Probably have to patch the Fortran code?

Activity

  1. bnavigator commented on May 17, 2020

    @bnavigator
    bnavigator
    on May 17, 2020
    CollaboratorAuthor

    A quick search on the internet reveals that various libs override XERBLA not to STOP.

    From the netlib docu:

    Installers may consider modifying the STOP statement in order to
    call system-specific exception-handling facilities.

    So Travis CI and my OpenSUSE system work fine with the sb10fd unit tests. Apparently not on the Archlinux system I tested this with...

  2. repagh commented on May 18, 2020

    @repagh
    repagh
    on May 18, 2020
    Member

    Is this dependent on the LAPACK version used? Which LAPACK does this link to?

  3. bnavigator commented on May 18, 2020

    @bnavigator
    bnavigator
    on May 18, 2020
    CollaboratorAuthor

    openblas 0.3.9 on Archlinux.

    libopenblas_pthreads 0.3.9 on OpenSUSE does not exhibit this behavior.

  4. bnavigator commented on May 19, 2020

    @bnavigator
    bnavigator
    on May 19, 2020
    CollaboratorAuthor

    Interestingly Job 387.4 for #129 should fail but does not, because of this bug.

    1528$ pytest --pyargs slycot --cov=$slycot_dir --cov-config=../Slycot/.coveragerc
1529============================= test session starts ==============================
1530platform linux -- Python 3.8.1, pytest-5.3.5, py-1.8.0, pluggy-0.13.1
1531rootdir: /home/travis/build/python-control/slycot-coverage
1532plugins: cov-2.8.1
1533collected 107 items                                                            
1534
1535tests/test_ab01.py F                                                     [  0%]
1536tests/test_ab08n.py ..                                                   [  2%]
1537tests/test_ag08bd.py ....                                                [  6%]
1538tests/test_analysis.py ...................                               [ 24%]
1539tests/test_examples.py .............                                     [ 36%]
1540tests/test_exceptions.py ..                                              [ 38%]
1541tests/test_mb.py ..........                                              [ 47%]
1542tests/test_mc.py ...                                                     [ 50%]
1543tests/test_sb.py ...The command "pytest --pyargs slycot --cov=$slycot_dir --cov-config=../Slycot/.coveragerc" exited with 0.

    The Travis jobs suffering from this bug use the Netlib reference LAPACK implementation. I wonder if my Archlinux system also uses that despite having compiled against openblas...

  5. repagh
    closed this as completedin #128on May 19, 2020
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